German AS No. 1 667 933 illustrates an apparatus of this type for treating milk or milk products, comprising a clearance space between a stationary housing and a disk rotating therein to guide therethrough the liquid to be treated and openings near the axis of rotation of the disk for introducing the liquid into the clearance space. The liquid is thereby conveyed by a separately arranged pump, for example a centrifugal pump into and through the apparatus. Thus altogether two drives are needed, namely, one for the disk and the other one for the centrifugal pump.
The purpose of this invention is to provide a better control or adjusting possibility of the duration and duration distribution of the food which is to be pasteurized, sterilized or heated, the capability of adjusting the construction to highly and low viscous fluids and the possibility of changing by a suitable selection of the clearance width, speed of the rotor, etc. the flow condition in the clearance space.
While one must expect below the so-called critical Taylor number a purely laminar shear flow, upon further increase of the speed said type of flow becomes unstable and the so-called Taylor vortices are created, which cause a secondary flow, which as is desired, substantially prevents in particular during a sterilization operation a baking on of the liquid. Upon further increase of the speed a turbulence is created. This too is for many purposes of use a desired flow condition, since through this the apparent viscosity and thus the temperature increase due to the inner friction is increased.
A further purpose of the invention exists in improving the conventional apparatus so that only one single drive is needed for both the conveying member and also for the member which effects the temperature increase of the liquid to be treated.